Title: Influence of Column Shortening in Reinforced Concrete and Composite High-Rise Structures
Author(s): M. M. Elnimeiri and M. R. Joglekar
Publication: Symposium Paper
Appears on pages(s): 55-86
Keywords: columns (supports); composite construction (concrete and steel); concrete construction; cracking (fracturing); creep properties; deformation; high-rise buildings; loads (forces); load transfer; measurement; serviceability; structural design; Construction
Differential elastic, creep, shrinkage, and thermal deformations of vertical concrete elements, columns, and walls in tall building structures require special attention to insure proper behavior for both strength and serviceability of the structure and the attached nonstructural elements. The long-term serviceability problems include out-of-level floors in both concrete and composite buildings, and cracking and deformations of internal partitions and external cladding elements. A procedure is developed to predict the long-term deformations of reinforced concrete columns, walls, and composite columns. The procedure incorporates the effects of concrete properties, construction sequence, and loading history. For composite columns, the effects of load transfer from the steel erection column to the reinforced concrete column are also included. Methods to minimize differential shortening of columns and walls are discussed. The methods involve corrections during both design and construction phases. Differential shortening effects for three tall buildings, in Chicago, which were designed using the procedure, are discussed. Results from six years of field measurements of column shortening are compared with predicted values.